Insulator for fence posts



p 7, 1.954 A. B. BUSSMANN, JR 2,688,654

INSULATOR FOR FENCE POSTS Filed Oct. 10, 1949 ATEORAZE'Y Patented Sept.7, 1954 UNITED STATES PATENT OFFICE INSULATOR FOR FENCE POSTS AloysiusB. Bussmann, Jr., St. Louis, Mo. Application October 10, 1949, SerialNo. 120,481

1 Claim.

This invention relates to improvements in insulators. More particularlythis invention relates to improvements in insulators which electricallyisolate electrified wires from supporting posts.

It is therefore an object of the present invention to provide animproved insulator which can electrically isolate an electrified wirefrom a supporting post.

In raising animals it is frequently desirable or necessary to confinethe animals to definite grazing areas; and such confinement is usuallyeffected by a fence or fences. While many different types of fences canbe used, electrified fences are preferable because they can be easilyerected and moved and can confine the animals safely and surely.Electrified fences usually consist of lightweight metal or wood postswhich support insulators; the insulators in turn supporting electrifiedwires. The insulators of an electrified fence are intended to maintainthe electrified wire in assembled relation with the fence posts whileelectrically isolating that wire from those posts; the efficiency of theelectrical insulators in preventing leakage of current to the fenceposts being an important measure of their value.

The insulators can be made with considerable thickness and of a hardinsulating material, and.

y when so made they will have sufficient electrical resistance toisolate the electrified wire from the fence posts. As long as thesurfaces of such insulators are dry and clean, those insulators caneffectively isolate the electrified wire from the fence posts; theresistance of the insulating material preventing passage of currentthrough the bodies of the insulators, and the dry clean surfaces of theinsulators preventing leakage of current along those surfaces. However,when the surfaces of the insulators become dirty and wet, as they willdo because of dust and rain, the water and dust tend to form paths alongthe surfaces of the insulators that can conduct current. Such conductionreduces the voltage of the electrified wire and reduces the utility ofthe electrified fence. To minimize any such conduction, the in sulatorsshould be made as elongated bodies, and the electrified wires should beheld in grooves adjacent those ends of the insulators which are remotefrom the fence posts. This arrangement increases the length andresistance .of the current leakage path along the surface of theinsulator.

Insulators of this type could be used successfully except for the factthat the fasteners for those insulators act to decrease the ability ofthose insulators to prevent conduction of current v from the electrifiedwire to the fence posts. For example, the great majority of thoseinsulators are secured to the fence posts by nails, bent wires, or boltswhich pass through axially-directed openings in the insulators; theheads of the nails or the loops of the wires or the nuts for the boltsbearing against the outer ends of the insulators and. forcing thoseinsulators against the fence posts. The heads of the nails or the loopsof the wires or the nuts for the bolts will be rather close to theelectrified wire supported by the insulators, and it will not be longbefore dust, rust from the nails or wires or bolts, or tanning solutionleaching from the leather washers used with the nails, will providecurrent leakage paths from the nail heads or wire loops to theelectrified wire; such current leakage paths conducting cur rent fromthe electrified Wire to the fastener, and the fastener conducting thatcurrent to the post. Those current leakage paths will thus vitiate theelectrical isolation thought to be provided by the elongation of theinsulators and by the holding of the electrified wires at those ends ofthe insulators which are remote from the fence posts. The presentinvention obviates such current leakage paths and yet attains intimateand positive securement of the insulators to the fence posts byproviding insulators which are held by fasteners that do not extendthrough to those ends of the insulators which are remote from the fenceposts.

The use of fasteners which do not extend through to those ends of theinsulators which are remote from the posts is additionally advanta geousbecause it minimizes electrical breakdown of the insulating material inthe bodies of the insulators. In the large majority of insulators usedon electric fences today, the thickness of insulating material betweenthe electrified wire and the fastener is at a minimum; the forming ofthe groove in the surface of the body reducing that thickness. As aresult, unless the insulating material between the wire-receiving grooveand the opening that receives the fastener is completely free of voidsor cracks, and unless the glazes on the surfaces of said groove andopening are perfect, current can pass through to the fastener from theelectrified wire. All of this is avoided by the present invention sincethe fastener is axially, as well as radially, spaced from thewire-receiving groove. The shortest straight line distance between awire in the groove and a fastener in the opening is not through the thinportion of the insulator adjacent the groove, but is through the thickportion of the insulator. Moreover, that straight line distance is alonga line inclined to the axis of the insulator and is thus much longerthan the wall thickness of that insulator. I

The insulators provided by the present invention have seats therein,which receive the fasteners and enable those fasteners to secure theinsulators to the fence posts; and those seats,

are spaced from the electrified wire distances, along the surfaces ofthe insulators, equal to or greater than the distances between theelectrified wires and the fence posts. With these insulators, thesecurement of the fasteners to the insulators and to the fence postswill not detract from the ability of the insulators to electricallyisolate the electrified wire from the fence posts; the surface distancealong each insulator between the post and the electrified wire being aprincipal determinant of the isolating efficiency of the insulator. Itis therefore an object of the present invention to provide an insulatorwith a seat therein which can receive a fastener and which is as farfrom the electrified wire as the electrified wire is from the post.

The electrical isolation of the fastener relative to the electrifiedwire is further assured by providing a number of abrupt changes ofcurvature in the surface of the insulator between the electrified wireand the seat for the fastener and between that wire and the post. Thesechanges of curvature increase the length of any electrical paths betweenthe electrified wire and the fastener or the post without increasing theoverall length of the insulator. Thus, increased electrical efficiencyis attained without any increase in the amount of insulating materialused in the insulator. It is therefore an object of the presentinvention to provide a number of abrupt changes of curvature in thesurface of an insulator between the electrified wire carried thereby andthe post or the seat for the fastener used with the insulator.

The outer end of the fastener used with the insulator provided by thepresent invention will be spaced wholly within the body of theinsulator. That end of the fastener will be lodged in the opening whichextends to theouter surface of the insulator, and that end of thefastener will be largely spared from direct contact with rain, sleet,ice and snow. Consequently, that end of the fastener will have lesstendency torust than will the ends of fasteners which project out of theinsulators. This. not only assures a longer life for the fastener but italso minimizes the amount of rust that could adhere to the surface ofthe insulator and provide a current leakage path. It is therefore anobject of the present invention to provide an insulator wherein theouter end of the fastener is disposed wholly within the body of theinsulator.

Other and further objects and advantages of the present invention shouldbecome apparent from an examination of the drawing and accompanyingdescription.

In the drawing and accompanying description a preferred embodiment ofthe present invention is shown and described but it is to be understoodthat'the drawing and accompanying description are for the purpose ofillustration only and do not limit the invention and that the inventionwill be defined by the appended claim.

In the drawing, Fig. l is an end view of an insulator that is made inaccordance with the principles and teachings of the present inven- Fig.2 is a side elevational view of the insulator shown in Fig. 1, I

Fig. 3 is a cross sectional side view of the insulator of Figs. 1 and 2,and it shows how that insulator can be secured to a fence post by aneye-bolt fastener,

Fi 4 is a side elevational view of the insulator, fastener and post ofFig. 3,

Fig. 5 is a cross sectional side view of the insulator of Figs. 1 and 2,and it shows how that insulator can be secured to a wooden post by ascrew, and

Fig. 6 is a side elevational view of the insulator of Figs. 1 and 2, andit shows that insulator secured to a post of L-shaped configuration.

Referring'to: the drawing in detail, the numeral Hl generally denotes abody of insulating material. That body has a base l2 and a recess Mextending into that base. The recess M has conical walls and a. fiatbottom; that recess having the form of a frustum of a. cone. Anv opening6, of circular cross section, is provided at the geometric center of thebody Hi, and that opening is contiguous with the recess Hi. The openingl6 opens out into a tapered circular opening 18; opening I8 extending tothe other end of the body Hi. The opening 58 is preferably hexagonal incross section, but that opening:

could be given a number of other circular cross sections. The opening l8has a taper, and that taper makes the outer end of opening it largerthan the inner end of that opening. The opening is and the opening. itdefine a. seat 28; that seat being intermediate the ends of the body It.The distance between the seat 2!) and the outer end of the body it isgreater than one half the length of that body.

A circular rim 22 is provided on the end face at the left hand end ofthe body If], and that. rim constitutes an abrupt change of curvaturefrom the interior of the opening it to a recess 24 of annular form inthe left hand end of the body Ill. The change of curvature is almost onehundred and eighty degrees between the surface of the opening 18 and theoutermost portion of the rim 22. A second abrupt change in curvatureoccurs at the junction of the rim 22 and the recess 24.

A wire-receiving groove 2 6 is provided adjacent the left hand end ofthe body H1, and that groove has six (6) fiat faces generally parallelwith the six (6) flat faces of the circular opening 18. With thisarrangement, the distance between the corresponding faces of groove 26and opening 18, through the insulating material of body Hi, will beuniform, except for the effect of the taper of opening E8. The groove 26coacts with the recess 24 to define an annular projection 28 at the lefthand end of the body ID. This annular projection provides an abruptchange of curvature between the recess 2 and the groove 2.6. Thewire-receiving groove 26 is adjacent the outer end of the body Hi, andit is disposed wholly outwardly beyond the seat 20.

A groove 30 and a groove 34 are provided in the exterior of the body Hibetween the wire.- receiving groove 2:5 and the base I2. The grooves 30and 34 define two annular projections 32 and 36; and the grooves 30 and3t and the projections 32 and 36. constitute abrupt changes of curvaturebetween the base I2 and the wirereceiving groove 26.

This construction provides a wire-receiving groove 26 which is spacedfrom the seat 20 and from the base I2. of the body Ill by substantial Istraight-line distances and by substantial surface distances. Thesurface distances are greater than the straight-line distances becauseof the abrupt changes of curvature provided by rimv 22, recess 24,grooves 36 and 34, and annular projections 28, 32 and 36. As a. result,if current could leak from a. wire held in the wire-receiving groove 26to the seat 26 or to the base I2 that current would have to travel alonger distance than the straight-line distance between thewire-receiving groove 26 and the base I2 or the seat 26. Of greatimportance is the fact that the seat 26 is disposed intermediate theends of the body I6 and that the current leakage path from groove 26 tothe seat 26 is equal to or longer than the current leakage path fromgroove 26 to the base I2, along the surface of body I6. Also of greatimportance is the fact that the wirereceiving groove is at that end ofthe body I6 which is remote from the post, while the seat 26 is at thatend of body I6 which is adjacent the post.

This avoids the decrease in the efficiency of the insulator experiencedwith prior insulators wherein the fastener was adjacent thewire-receiving groove, or wherein the wire-receiving groove was tooclose to the post.

The opening I6 in the body I6 is dimensioned to receive the threadedportion of an eyebolt 38. The recess I4 extending inwardly from the baseI2 is dimensioned to receive part of the curved portion of the eyebolt38, and to permit that part of the curved portion to be drawn inwardlyof the body I6. The circular opening I8 is dimensioned to snugly receivea nut 46 which can be threaded onto the threaded end of the eyebolt 38.To assemble the eyebolt 38 with the insulator, it is only necessary toinsert the threaded end of the eyebolt 38 through the opening I6 whileholding the body I6 in position so gravity will cause the nut 46 to fallto the bottom of the opening I8. It is then a simple matter to eitherhold the eyebolt 38 and rotate the body ID or to hold the body I6 androtate the eyebolt 38. In either event, the threads on the end of theeyebolt 38 will engage the threads of the nut 46 and cause the nut 46 tobe held in engagement with the eyebolt 38. Once the threads of theeyebolt 38 have engaged the threads of the nut 46, the eye of theeyebolt 38 can be telescoped over the top of a fence post 42. Thereafterthe eyebolt 38 and the insulator can be moved downwardly until theyreach the desired height, whereupon a few additional turns of the bodyID will lock the eyebolt and insulator in position. At that time the nut46 will be pressed firmly against the seat 28, and the eye of theeyebolt will tightly encircle post 42. Solid securement with the post 42is assured because the recess I4 is dimensioned to receive part of thecurved portion of the eye of the eyebolt, thus enabling that eye toprovide loop contact with the post 42 while the post 42 has line contactwith the opposite edges of the base I 2. This arrangement facilitatessuch a complete securement of the post and insulator that there is nodanger of the insulator sliding down the post.

When pressed against the seat 26, the nut 46 will be spaced from thewire-receiving groove 26 a distance, along the surface of body I6, thatis equal to or longer than the distance, along the surface of body III,between the wire-receiving groove 26 and the base I2. This means thatthe eyebolt fastener 38 does not in any way detract from the electricalisolation of the electrified wire from the post; a principal limitingfactor to such electrical isolation being the distance along the surfaceof the body I6 between the wire in the groove 26 and the post 42. Thisis in sharp contrast with insulators which have axial openings thatreceive elongated nails or bent wires or bolts, because in thoseinsulators the heads of the nails or the loops of the wires or the nutsfor the bolts are closely adjacent the wire-receiving grooves andprovide short leakage paths. Moreover, the nut 46 is spaced from thewire-receiving groove 26 by three abrupt changes of curvature: the firstchange of curvature being between the opening I8 and the rim 22, thesecond change of curvature being between the rim 22 and the recess 24,and the third change of curvature being between the recess 24 and theannular projection 28. Because the seat 26 is spaced from thewire-receiving groove 26 by a distance greater than the distance betweenthat groove and the post 42, and because the seat 26 is spaced from thewire-receiving groove 26 by three abrupt changes of curvature, theelectrical isolation of an electrified wire in groove 26 will not bereduced by the presence of a fastener pressing against the seat 20.

It should also be noted that the shortest straight line distance betweena wire in groove 26 and a fastener in opening I8 is not through the thinwall adjacent groove 26. Instead, that straight line distance is throughthe thick wall portion of the body I6. Moreover, by being inclined tothe axis of the body, that distance is much longer than the wallthickness of the body I6.

In the event rain, snow or ice is driven into the opening I8, that rain,ice or snow will run out because of the taper of that opening. Moreover,that taper will act to guide the nut 46 as it is dropped downwardlytoward the seat 26. That taper would also guide a screw or nail droppedtoward the seat 26.

The insulator provided by the present invention can be secured to postsby a wood screw, as shown particularly in Fig. 5. The seat 26 receivesthe head of a wood screw 44, and the threaded end of that wood screwwill seat in a wooden post 46. In securing the insulator to the post 46,it is only necessary to turn the insulator so the opening I8 isvertically directed, drop the screw 44 into that opening with thethreaded end downward, shake the insulator until the threaded end ofscrew 44 passes through the opening I6, and place a screw driver in theopening I8 so its blade will seat in the slot in the head of the screw44. Thereafter, it is a simple matter to place the end of the screw 44in engagement with the wooden post and rotate that screw until it bitesinto the wood of the post and pulls the base I2 of the insulator solidlyagainst that post. The insulator could also be held against a woodenpost by a nail, as by using a nail set to drive the nail home. In thecase of the screw and the nail, the heads of those fasteners will pressagainst the seat 26, thus being spaced from the wire-receiving groove 26and being isolated from the electrified wire in that groove.

The insulator can be secured to posts of L- shaped configuration, asshown in Fig. 6. In that case, a J-bolt 48 is secured to the insulatorby a nut, not shown, in the same manner as the eyebolt of Fig. 3 issecured to its insulator. However, the J of the J-bolt 48 does notencircle the post; instead it is set so it presses against one face ofthe post 56. The rotation of the insulator body I6 will tighten the nuton the threaded end of J portion of J-bolt 48 and will tend to lock theJ portion of J-bolt 48in position against the post. In each instance,the fastener is spaced from the wire-receiving groove a surface distanceequal to or longer than the surface distance between that wire-receivinggroove and the post. This is due to the spacing of the seat intermediatethe ends of the insulator.

Whereas a preferred embodiment of the present invention has been shownand described in the drawing and accompanying description it shouldbeobvious to those skilled in the art that various changes may be madein the form of the invention without affecting the scope thereof.

What I claim is:

An insulator that is adapted to hold an elec trified wire in assemble-:1relation with a support while electrically isolating said electrifiedwire from said support, said insulator comprising an elongated body ofinsulating material, said elongated body being of circular cross-sectionthroughout the major portion of the length thereof and havingalternating annular grooves and projections on the exterior of saidmajor portion of the length thereof, a wire receiving groove in theexterior of said elongated body adjacent that end or said elongated bodywhich is remote from the base of said elongated body, said wirereceiving groove being spaced from said end of said elongated body by asmoothly rounded annular projection that extends radially outwardlybeyond said wire receiving groove and being adjacent one of said annularprojections in said major portion of the length of said elongated body,said one annular projection in said major portion of the length of saidelongated body being smoothly rounded and extending radially outwardlybeyond said wire receiving groove, said wire receiving groove having asthe bottom thereof a plurality of contiguous planes constituting aprism, a passageway extending through said elongated body adapted toreceive means for holding said elongated body in assembled relation withsaid support, said passageway being co-axial with the long axis of saidelongated body and having three portions of difierent length andcross-sec tion throughout its length, one of said portions having as thewall thereof a plurality of contiguous planes forming a prismaticenclosure, the contiguous planes of said wall of the first said portionbeing substantially parallel to the said contiguous planes of said wirereceiving groove, said first portion extending from said end of saidelongated body a distance greater than half the length of said elongatedbody, a second of said portions being contiguous with said first portionand being of circular cross-section smaller than the cross-section ofthe first said portion, said second portion being short, a third of saidportions being a recess that extends inwardly from said base of saidelongated body and being of gradually decreasing cross-section and beingcontiguous with said second portion, said holding means extendingthrough said third portion and said second portion and extending intosaid first portion when the insulator is holding said electrified wirein assembled relation with said support, said portions of saidpassageway forming a continuous imperforate wall for said passageway.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 836,122 Locke Nov. 20, 1906 927,321 Bond July 6, 19091,720,181 Kyle July 9, 1929 1,736,043 Kyle NOV. 19, 1929 2,191,171 Leeet a1. Feb. 20, 1940 2,440,748 Johnson May 4, 1948 2,450,730 I-Iord Oct.5, 1948 2,468,907 Wilson et a1. May 3, 1949 FOREIGN PATENTS NumberCountry Date 146,911 Germany Dec. 19, 1903 161,092 Germany May 31, 190518,903 Denmark June 8, 1914

